Hello. I'm sorry you're uncomfortable. Without an examination it's not possible to diagnose your condition, but there are a couple of possibilities here:
If the red bump is right at the edge of your anal opening, it's most likely a hemorrhoid
, which is simply a varicose vein
in the network of blood vessels surrounding your rectum and anus. Hemorrhoids are quite common; those that become clotted (a thrombosed hemorrhoid) can be exquisitely painful. Hemorrhoids can generally be addressed with over-the-counter medications (e.g., Preparation-H, Tucks pads, etc.), warm sitz baths, ice packs, and keeping the anal area clean. (Wiping after a bowel movement with moistened toilet paper is helpful.)
If the red bump is near, but not on, the edge of your anal opening, it might be a perianal abscess
, which results from bacterial infection of an anal crypt (a small recess just inside the anus). Anal abscesses tend to get progressively worse until they're treated, which usually requires antibiotics and surgical drainage
If you're not in severe pain
, I suggest you treat this bump as a hemorrhoid. If your discomfort worsens or if the bump persists, see your doctor for an evaluation.